Male Savannah Sparrows Provide Less Parental Care With Increasing Paternity Loss

Male parental care can significantly affect fledging success and, therefore, is a strong target of both natural and sexual selection. However, for songbird species that exhibit extra-pair paternity, males may reduce parental care based on how much paternity they have lost in a brood. We studied Passerculus sandwichensis (Savannah Sparrow) male parental care relative to the proportion of extra-pair young in the nest, to see if males adjusted care in response to increasing loss of paternity. Males brought less food (mass) with increasing rates of extra-pair paternity, although male provisioning did not influence fledging success. These results contrast with a previously published study of an island population of this species, where males provided more parental care with increased loss of paternity. We hypothesize that high rates of annual survival in this mainland population, where males have a greater potential for reproduction in future years, may explain this difference in behavior